Apparatus for electric heating.



PATENTED OCT. 4, 1904.

W. S. HURRY.

APPARATUS FOR ELECTRIC HEATING.

APPLIOATION FILED JUNE 28,1904.

2 SHEETS-SHEET 1.

NO MODEL.

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PATENTED 001'. 4, 1904.

W. S. HORRY.

APPARATUS FOR ELECTRIC HEATING.

APPLICATION TILED JUNE 28,1904.

2 SHEETS-SHEET 2.

N0 MODEL.

No. 771,250. Patented October 4, 1904 UNITED STATES PATENT OFFICE.

WILLIAM SMITH HORRY, OF NIAGARA FALLS, NEIV YORK, ASSIGNOR TO UNION CARBIDE COMPANY, OF NIAGARA FALLS, NEW YORK, A (JOR- PORATION OF VIRGINIA.

APPARATUS FOR ELECTRIC HEATING.

SPECIFICATION forming part of Letters Patent No. 771,250, dated October 4, 1904. Application filed June 28, 1904. Serial No. 214,484. (No model T w it m y OOYWWTM of an electric stack-furnace designed for the Be t known that I, WVILLIAM SMITH HOERY, commercial utilization of the invention. a sub3ect of the King of Great Britain, resid- The circular body to be heated (shown in ing at Niagara Falls, in the county of Niagara Fig. 1) may be a disk of metal or a metallic 5 and State of New York, have invented certain crucible, but is more especially a layer of calnew and useful Improvements in Apparatus cium carbid or of carbid-forming materials, for Electric Heating, of which the following such as exists in the lower part of the furis a specification. nace shown in Figs. 3, 4 when in normal This invention relates to apparatus for elecworking operation. The terminals of the IQ trically heating a body of conducting matesource of polyphase current, here shown as rial, especially a mixture of a metallic comtwelve in number, are placed substantially in pound and a reducing agent and specifically contact with the edge of the disk at equidisa mixture of lime and carbon, for the productant points, (numbered 1 to 12.) The source tion of calcium carbid. of current may be a dynamo having a fixed 5 The invention contemplates the use of a external armature consisting of a circular polyphase alternating current, preferably one Gramme ring with continuous winding, leads with many phases, the paths of the several being taken out from the winding at twelve 5 phases beingso distributed within the conductequidistant points to the several terminals in ing-body as to effect an even heating thereof. contact with the disk. Vithin the armature 20 The invention is carried out by causing difis a bipolar revolving field. The maximum ferent phases of the currentto simultaneously electromotive force of this generator is asflow along paths which cross each other sumed to be two hundred volts and the cur- 7 through the body and causing each phase to rent carried by the maximum volts to be passtraverse a path of resistance corresponding to ing between the terminals 1 and 7 of Fig. 1,

5 the electromotive force of that phase. fall of potential in the dynamo and conductors The body to be heated is preferablyacircular being neglected. A number of currents will disk, theactive terminals ofthe source of polythen simultaneously flow through the disk phase current being placed substantially in along paths indicated by the broken lines, the contact with the body at various equidistantpotential difference between the terminals at 3 points around its periphery and the terminals the end of each path of current-flow being inbetween which the maximum potential diiferdicated by the numerals applied to the sevence is set up being arranged at opposite ends eral lines. It will thus be seen that the elecof a diameter of the circular disk, this diamtromotive force tending to drive a current eter successively shifting between successive along each path substantially corresponds to 35 pairs of oppositeterminals followingtheshiftthe resistance of that path, thus giving an ing phases in the windings of the dynamo or equal current along every line. As the field other source of current. revolves within the dynamo the phase of maxi- 5 Referring to the accompanying drawings, mum electromotive force shifts from ter- Figure 1 is a diagram illustrating the heating minals 1 7 to 2 8 and then to 3 9, and so on.

4 of a circular disk by a current of six phases It will thus be seen that thedisk is heated to a having twelve active terminals arranged in practically uniform temperature throughout. contact with the edge of the disk. Fig. 2 is a Figs. 3 and 4 show a furnace for the pro- 9 horizontal section of a square electric furnace duction of calcium carbid designed to reemploying a current of two phases, the curceive a current of two thousand kilowatts or 45 rent being distributed to the electrodes by more. The furnace comprises an annular transformers whose windings are shown in stack 21, of refractory material, such as firediagram; and Figs. 3and4 area vertical axial brick, having at its upper end a suitable section and ahorizontal section, respectively, mechanism 22 for introducing raw material nections.

passing adjustably through the sides of the stack. Each horizontal series comprises twenty-four electrodes, each connected to one terminal of a dynamo or transformer giving a current of twelve phases. A tap-opening 25 for the molten carbid extends through one side of the stack near its lower end. This tap-opening, however. may be closed and the carbid maintained at or above the level of the electrodes, in which case it can be tapped ofl through one of the openings which receives an electrode upon withdrawing the latter, such as the lower right-hand electrode 2A in Fig. 3. 1n employing this furnace to produce calcium carbid an initial charge consisting of lime and carbon is fed in through the top of the furnace. .This charge may be the well-known one containing large pieces of coke, which lie in contact with each other at various points, and thereby afford direct paths for the flow of current, the lime being distributed in the interstices between pieces of coke. If the normal charge, however, consists of a non-conducting mixture of coke and lime, the furnace must be first put in operation by the use of a conducting charge or by otherwise providing. initial paths for the flow of current. As soon, however, as current passes through a conducting-body in the lower part of the furnace the temperature soon rises to a point where the charge above is preheated by conduction and radiation and by the waste gases rising from the zone of reduction to a'temperature which will enable it to act as a resistance-conductor when it descends into the paths of current-flow. In normal working condition the body of material between the electrodes may consist of molten or partly-molten carbid or of incandescent but unreduced material, or in part of both. The reduction is carried out in a continuous manner by tapping out the molten carbid and supplying fresh material as required. As the current density for each electrode cannot be carried above a certain limit, the total energy which can be employed in heating the charge depends on the number of electrodes, which may be increased as desired either by arranging a greater number in the same horizontal series or by using any desired number of superposed horizontal series. The use of a large number of electrodes is a desirable feature, since it permits the use of relatively small electrodes without unduly heating them or their terminal con- The use of a current of a large Practically the maximum voltage of the generator is always maintained between one pair of electrodes, the working current thus being the maximum current of the generator instead of varying from zero to a maximum. For the same reason the total cross-section of the electrodes may be smaller than for a furnace of the same capacity using single-phase current, effecting a saving in this respect of about thirty per cent., by weight. Any electrode may also be removed and replaced by another without noticeably interfering with the operation of the furnace. It is evident that by this invention the advantages of the direct current are retained without subjecting the furnace charge to the electrolytic effect that accompanies such current.

A circular furnace is preferred, since it exposes a minimum periphery for the loss of heat by radiation. The furnace may, however, be polygonal or square. Fig. 2 shows a square furnace 25 in horizontal section through the electrodes. A group of four electrodes 26 is shown passing through each side of the furnace. The current for this furnace is furnished by a system of transformers the windings of which are shown in diagram. Two distinct single-phase transformers are employed each receiving a separate current at a potential difference of, say, two thousand volts. Each of these transformers has two independent secondary windings arranged to generate an electromotive force of, say, fifty volts. In the figure, A B indicates the single primary winding of one transformer, A B the first secondary winding, and A B the second secondary winding. The single primary winding of the second transformer is marked 0 D and the corresponding first and second secondary windings C D and C D respectively. The current through primary 0 D should lag one quarter-phase behind that through primary A B. The two transformers are thus equivalent to a single one receiving two-phase current. Terminals are led out from the ends of the first secondary of one transformer.

to the end electrodes of one group of four and from the ends of theother secondary of the same transformer to the end electrodes of the opposite group of four. ate electrodes of each group are connected to intermediate points of the corresponding secondary. The maximum electromotive force is thus applied to opposite electrodes; but cur- 7 rent also flows across the furnace from each each other through said body, as set forth.

The intermedi- 2. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body, as set forth.

3. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to flow along paths which cross each other through said body and for progressively shifting the path of the phase of maximum electromotive force, as set forth.

4. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body and for progressively shifting the path of the phase of maximum electromotive force, as set forth.

5. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to flow along paths which cross each other through said body and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

6. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

7 An apparatus for electrically heating a body of conducting material. comprising means for causing different phases of a polyphase current to flow along paths which cross each other through said body, for progressively shifting the path of the phase of maximum electromotive force,and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

8. An apparatus for electrically heating a body of conducting material, comprising means for causing different phases of a polyphase current to simultaneously flow along paths which cross each other through said body, for progressively shifting the path of the phase of maximum electromotive force, and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

9. An apparatus for electrically heating a body of conducting material, comprising a source of polyphase current and active terminals placed substantially in contact with the body at such points that diiferent phases of the current simultaneously flow between several of said terminals and along paths which cross each other through said body, as set forth.

10. An apparatus for electrically heating a body of conducting material, comprising a source of polyphase current and active terminals placed substantially in contact with the body at such points that diflerent phases of the current simultaneously flow between several of said terminals and along paths which cross each other through said body, and that each phase traverses a path of resistance corresponding to the electromotive force of that phase, as set forth.

11. An apparatus for electrically heating a circular body of conducting material, comprising a source of polyphase current and active terminals placed substantially in contact with the body at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other through said body, as set forth.

12. An apparatus for electrically heating a circular body of conducting material, comprising a source of polyphase current and active terminals placed substantially in contact with the body at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other through said body, and that each phase traverses a path of resistance corresponding to the electromotive force of that phase, as set forth.

13. An apparatus for electrically heating a circular body of conducting material, comprising a source of polyphase current and active terminals placed substantially in contact with the body at such points around its periphery that different phases of the current simultaneously flow beween several of said terminals and along paths which cross each other through said body, and that each phase traverses a path of resistance corresponding to the electromotive force of that phase, with the phase of maximum electromotive force passing substantially along a diameter of the circular body, as set forth.

14:. An apparatus for electrically reducinga circular body consisting of a mixture of a compound and a reducing agent, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the products of reduction thereof at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other, as set forth.

15. An apparatus forelectricallyreducinga circular body consisting of a mixture of a compound and a reducing agent, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the products of reduction thereof at such points around its periphery that differ ent phases of the current simultaneously flow between several of said terminals and along paths which cross each other, and that each phase traverses a path of resistance corresponding to the electromotive force of that phase, as set forth.

16. An apparatus for producing carbids by electrically heating a body of carbid-forming materials, comprising means for causing different phases of polyphase current to pass through said body or the carbid produced therefrom, along paths which cross each other, as set forth.

17. An apparatus for producing carbids by electrically heating a body of carbid-forming materials, comprising means for causing clifferent phases of polyphase current to pass through said body or the carbid produced therefrom,along paths which cross each other, and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, as set forth.

18. An apparatus for producing carbids by electrically heating a circular body of carbid- .forming materials, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the carbid produced therefrom, at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other, as set forth.

19. An apparatus for producing carbids by electrically heating a circular body of carbidforming materials, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the carbid produced therefrom, at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other, and that each phase traverses a path of resistance corresponding to the electromotive force of that phase, as set forth.

20. An apparatus for producing carbids by electrically heating a body'of carbid-forming materials, comprising means for causing different phases of polyphase current to pass through said body or the carbid produced therefrom, along paths which cross each other, and means for tapping off the molten carbid and feeding in fresh materials as required, as set forth.

21. An apparatus for producing carbids by electrically heating a body of carbid-forming materials, comprising means for causing clifferent phases of polyphase current to pass through said body or the carbid produced therefrom, along paths which cross each other, and for causing each phase to traverse a path of resistance corresponding to the electromotive force of that phase, and means for tapping ofi the molten carbid and feeding in fresh materials as required, as set forth.

22. An apparatus for producing carbids by electrically heating a circular body of carbidforming materials, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the carbid produced therefrom, at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other, and means for tapping off Ethe molten carbid and feeding in fresh materials as required, as set forth.

23. An apparatus for producing carbids by gelectrically heating a circular body of carbidforming materials, comprising a source of polyphase current and active terminals placed substantially in contact with the body or the ,carbid produced therefrom, at such points around its periphery that different phases of the current simultaneously flow between several of said terminals and along paths which cross each other, and that each phase traverses 'a path of resistance corresponding to the electromotive force of that phase, and means for .tapping off the molten carbid and feeding in fresh materials as required, as set forth.

24:. An apparatus for electrically heating a body of conducting material, comprising a series of removable electrodes placed sub stantially in contact with the body at various points around its periphery, and meansfor causing different phases of a polyphase current to simultaneously flow between several of said electrodes and along paths which cross each other through said body, as set forth.

25. An apparatus for electrically melting a body of conducting material, comprising retaining-walls, a series of removable electrodes passing through the Walls and substantially in contact with the body at various points around its periphery, and means for causing different phases of a polyphase current to simultaneously flow between several of said electrodes and along paths which cross each other through said body, the arrangement being such that the removal of one of the electrodes permits the molten product to escape through the opening left thereby, as set forth.

Intestimony whereof I aflix my signature in presence of two witnesses.

\VILLIAM SMITH HORRY.

Witnesses:

E. F. PRICE, GEO. H. DANFORTH. 

